test_canvas_readback_before_draw.html

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This test runs only with pattern: early_beta_or_earlier OR os == 'mac' && arch == 'aarch64' OR os == 'win'
Manifest: dom/webgpu/tests/mochitest/mochitest.toml

<!doctype html>

<html>

  <head>

    <meta charset="utf-8" />

    <script src="/tests/SimpleTest/SimpleTest.js"></script>

    <link rel="stylesheet" href="/tests/SimpleTest/test.css" />

  </head>

  <body>

    <canvas id="canvas" width="16" height="16"></canvas>

    <script>

      async function testBody() {

        const adapter = await navigator.gpu.requestAdapter();

        const device = await adapter.requestDevice();

        const format = navigator.gpu.getPreferredCanvasFormat();

        const canvas = document.getElementById("canvas");

        const context = canvas.getContext("webgpu");

        context.configure({ device, format });

        // Read back the canvas, before it is composited.

//

        // Note: sleeping would not be sufficient for compositing to happen. For

        // the canvas to be composited, it needs to be used in a submitted

        // command buffer.

        const dataUrl = canvas.toDataURL();

ok(

          dataUrl.startsWith("data:image/png;base64,"),

          "toDataURL should return a PNG data URL"

);

        ok(dataUrl.length > "data:image/png;base64,".length, "data URL should be non-empty");

      SimpleTest.waitForExplicitFinish();

      testBody()

        .catch(e => ok(false, "Unhandled exception " + e))

        .finally(() => SimpleTest.finish());

    </script>

  </body>

</html>